Barrel arbor and ratchet wheel arrangement for watches



H. STAMM BARREL ARBOR AND RATCHET WdEEL ARRANGEMENT FOR WATCHES Filed Feb. 4, 1959 jIJVNrO d HEINRICH STAHM United States Patent 3,119,227 BARREL ARBOR AND RATCHET WHEEL ARRANGEMENT FOR WATCHES Heinrich Stamm, Grenchen, Canton of Solothnrn, Switzerland, assignor to ETA A.G. Ebauches-Fabrik Filed Feb. 4, 1959, Ser. No. 791,198 Claims priority, application Switzerland Feb. 6, 1958 4 Claims. (Cl. 588t)) This invention relates to barrel arbor and ratchet wheel arrangements and in particular to such arrangements in which a ratchet wheel visible from the bridge side of the watch movement is located above a barrel bridge on to a barrel arbor portion extending above the barrel bridge.

In most of the watches of this type known in the art, the ratchet wheel is fixed to the barrel arbor portion projecting above the barrel bridge by means of a fixing screw screwed into the barrel arbor. The ratchet wheel is rigidly connected to the barrel arbor for rotary motions by means of a square portion provided on the barrel arbor and engaged in a corresponding opening provided in the center of the ratchet wheel. Moreover, the ratchet wheel is axially held in place on the barrel arbor by means of a large cylindrical head portion of the fixing screw which presses the ratchet wheel in axial direction against a shoulder of the barrel arbor.

Since the thickness of a watch movement very often depends on the thickness of the barrel and of the elements superposed upon the barrel, the watchmakers have attempted to render the fixing means of the ratchet wheel to the barrel arbor as thin as possible in order to make thin watch movements. A first attempt made in this respect consisted in contersinlcing partly or entirely the cylindrical head of the fixing scre w of the ratchet wheel within the latter. This attempt is, however of no great help since the barrel arbor bearing carried by the barrel bridge, the ratchet wheel fixed on to the barrel arbor portion projecting above the barrel bridge and the head of the fixing screw of the ratchet wheel are still superposed on the barrel and since the thickness of these three elements cannot obviously be reduced under predetermined limits.

It has also been attempted in some devices known in the art to avoid superposing one of the three elements mentioned above upon the barrel. Thus ratchet wheels have been provided with a central screw threaded projeetion. It has also been attempted to make ratchet wheels with a central tapped bore in order to screw said ratchet wheels directly on to a threaded portion of the barrel arbor. Still a further attempt consisted in providing the ratchet wheels with a square central opening having inclined edges for engagement on a square undercut portion of the barrel arbor being somewhat smaller than said opening of the ratchet wheel. These three attempts have, however, the drawback that the ratchet wheel is safely held on the barrel arbor only as long as the watch spring is wound. But upon vanishment of the tension of this spring as for instance when the watch has run down or when the spring breaks off, the ratchet wheel could fall from the barrel arbor.

It is therefore an object of this invention to provide a barrel arbor and ratchet wheel arrangement in which the ratchet wheel is fixed to the barrel arbor in an absolutely safe manner and in which only two of the three elements mentioned above (barrel bridge, ratchet wheel, fixing screw head) are still superposed upon the barrel.

Still further objects of the invention will become apparent in the course of the following description.

One embodiment of the barrel arbor and ratchet wheel arrangement according to the invention is represented 3,119,227 Patented Jan. 28, 1964 "ice diagrammatically and by way of example in the drawings annexed to this specification.

In the drawings:

FIG. 1 is a cross-sectional view along line 'I-I of FIG. 2,

FIG. 2 is a plan view of said embodiment,

FIG. 3 is a perspective partial 'view of the barrel arbor of FIG. 1 and,

FIG. 4 is a perspective partial view of the central portion of the ratchet wheel of FIG. 1.

The barrel arbor 1 partly represented in the drawings is journalled in the well known manner in bearings provided in a base plate (not shown) and in a barrel bridge 2. The barrel 3, which [is only represented in part, is rotatively mounted on the barrel arbor 1 in the manner well known in the art. The arbor 1 is provided with an end portion 4 extending above the barrel bridge 2 and having a square cross-section and a conical end face 5. As best shown in FIG. 3, the conical end face 5 intersects the side faces of the end portion 4 so that the side faces of the barrel arbor end portion 4 have a maximum height a at the corners thereof and a minimum height b intermediate the corners. The portion 4 of arbor 1 is limited underward by an arbor shoulder 6 also located above the barrel bridge 2 and formed at the upper end of the pivot 7 of the barrel arbor 1, which is journalled in the bearing carried by the barrel bridge 2.

The rachet wheel 8 is provided with a central square opening 9 as well as with a truncated conical seat '10 intersecting the races defining the square opening 9 along intersecting lines 14 best shown in FIG. 4. The greatest diameter of this truncated conical seat 10 and the diagonal of the opening 9 are approximately equal. The seat It) is formed by the upper faces of tour inner projections 11 of the ratchet wheel having the form of circular segments as shown in FIG. 2. The opening 9 is adjusted as exactly as possible with respect to the end portion 4 of arbor 1 in order that the ratchet wheel 8 can easily be set on portion 4 and will rigidly be connected to arbor 1 for rotary movements.

In axial direction, the ratchet wheel 8 is held in place on the barrel arbor portion 4 by means of a fixing screw 12. The screw 12, which is screwed into a tapped blind hole of the barrel arbor 1, is provided with a conical head '13 lying on the seat 10 of the ratchet wheel. The portion of the latter, which is formed by the four projections 11, is thus firmly gripped by the screw 12 between the head portion 13 thereof and the shoulder 6 of arbor 1. To prevent the head 13 of screw 12 from coming in contact with the portion 4- of arbor 1 instead of with the upper faces of the inner projections 11 of the ratchet wheel, the concave end face 5 of portion 4 has the same inclination both as the conical under face of the screw head 13 and as the seat 16 on the ratchet wheel and said end face 5 is located somewhat below the seat 10 as shown in FIG. 1.

With respect to the barrel arbor and ratchet wheel arrangements known in the art, the arrangement described above has the advantage that the elements which ensure both rig-idly fixing the ratchet wheel to the barrel arbor for rotary movements and axially holding said ratchet wheel on said arbor are not superposed on one another but set in juxtaposition. In the arrangement improved in accordance with the invention, the ratchet wheel 8 is rigidly fixed to the barrel arbor 1 for rotary movements by means of the four axial projections of said arbor which are located at the four edges of its portion 4 and which are engaged between the four inner projections 11 of the ratchet wheel 8.

Even with a very thin ratchet wheel, the arrangement according to the invention is amply sulficient for ensuring a satisfactory rigidity to the ratchet wheel and barrel arbor arrangement. Moreover, there is place enough Within the ratchet wheel for the head 13 of the fixing screw 12, since the height of head 13 and the thickness of the ratchet wheel 8 can be chosen approximately equal as shown in FIG. 1.

Although one embodiment of the invention has been described in detail hcreabove, it will be understood that various changes in the shape, sizes and arrangement of parts could be resorted to without departing from the spirit of the invention or sacrificing the advantages thereof.

I claim:

1. In a watch, in combination, a ratchet wheel having a top face and a bottom face spaced a given distance from each other, said ratchet wheel being formed with a central opening thercthrough having an upper portion defined by a conical f cc and a lower portion of polygonal cross section and defined by faces intersecting each other along edges substantially parallel to the axis of said conical face and intersecting said conical face of said upper portion along intersection lines having their highest points at said edges and curving downwardly therefrom toward said bottom face; a barrel arbor having a shoulder engaging said bottom face of said ratchet wheel and a ratchet wheel receiving end portion having a cross section substantially equal to said cross section of said lower portion of said central opening and projecting upwardly from said shoulder through said central opening and extending with corner portions thereof upwardly beyond the lowest portions of said intersection lines, said ratchet wheel receiving end portion having a concave conical end face of substantially the same inclination as said conical face of said central opening of said ratchet wheel but with an apex below the apex of said conical face of said ratchet wheel opening; and a holding screw screwed into said arbor and having a conical head located in said central opening of said ratchet wheel and engaging with the conical surface thereof said conical face of said upper opening portion so as to press said ratchet wheel against said shoulder of the arbor.

2. In a watch, in combination, a ratchet wheel having a top face and a bottom face spaced a given distance from each other, said ratchet wheel being formed with a central opening therethrough having an upper portion defined by a conical face and a lower portion of polygonal cross section and defined by faces intersecting each other along edges substantially parallel to the axis of said conical face and intersecting said conical face of said upper portion along intersection lines having their highest points at said edges and curving therefrom downwardly toward said bottom face; a barrel arbor having a shoulder engaging said bottom face of said ratchet wheel and a ratchet wheel receiving end portion having a cross section substantially equal to said cross section of said lower portion of said central opening and projecting upwardly from said shoulder through said central opening and extending with corner portions thereof upwardly beyond the lowest portions of said intersection lines; and a holding screw screwed into said barrel arbor and having a conical head located in said central opening of said ratchet wheel and engaging with the conical surface thereof said conical face of said upper opening portion so as to press said ratchet wheel against said shoulder of said arbor, said ratchet wheel receiving end portion being formed at the free end thereof with a clearance face spaced from said conical surface of said conical head of said holding screw.

3. In a watch, in combination, a ratchet wheel having a top face and a bottom face spaced a given distance from each other, said ratchet wheel being formed with a central opening therethrough having an upper portion defined by a conical face and a lower portion of polygonal cross section and defined by faces intersecting each along edges substantially parallel to the axis of said conical face and intersecting said conical face of said upper portion along intersection lines having their highest points at said edges and curving therefrom downwardly toward said bottom face; a barrel arbor having a shoulder engaging said bottom face of said ratchet wheel and a ratchet wheel receiving end portion having a cross section substantially equal to said cross section of said lower portion of said central opening and projecting upwardly from said shoulder through said central opening and extending with corner portions thereof upwardly beyond the lowest portions of said intersection lines, said ratchet wheel receiving end portion having a concave conical end face of substantially the same inclination as said conical face of said central opening of said ratchet wheel but with an apex below the apex of said conical face of said ratchet wheel opening; and a holding screw screwed into said barrel arbor and having a conical head of a height substantially equal to said distance between top and bottom faces of said ratchet wheel and a top face flush with said top face of said ratchet wheel, said conical head being located in said central opening of said ratchet wheel and engaging with the conical surface thereof said conical face of said upper opening portion so as to press said ratchet wheel against said shoulder of said arbor.

4. In a watch, in combination, a ratchet wheel having a top face and a bottom face spaced a given distance from each other, said ratchet wheel being formed with a central opening therethrough having an upper portion defined by a conical face and a lower portion of square cross section having a diagonal substantially equal to the maximum diameter of said conical face and defined by faces substantially parallel to the axis of said conical face and intersecting said conical face of said upper portion along intersection lines having their highest points at said top face and curving downwardly therefrom toward said bottom face; a barrel arbor having a shoulder engaging said bottom face of said ratchet wheel and a ratchet wheel receiving end portion having a cross section substantially equal to said cross section of said lower portion of said central opening and projecting upwardly from said shoulder through said central opening and extending with corner portions thereof upwardly beyond the lowest portions of said intersection lines; and a holding screw screwed into said barrel arbor and having a conical head located in said central opening of said ratchet wheel and engaging with the conical surface thereof said conical face of said upper opening portion so as to press said ratchet wheel against said shoulder of said arbor, said ratchet wheel receiving end portion being formed at the free end thereof with a clearance face spaced from said conical surface of said conical head of said holding screw.

References Cited in the file of this patent UNITED STATES PATENTS 1,382,799 Purple June 28, 1921 FOREIGN PATENTS 156,980 Switzerland Nov. 16, 1932 237,430 Switzerland Apr. 30, 1945 262,327 Switzerland June 30, 1949 

1. IN A WATCH, IN COMBINATION, A RATCHET WHEEL HAVING A TOP FACE AND A BOTTOM FACE SPACED A GIVEN DISTANCE FROM EACH OTHER, SAID RATCHET WHEEL BEING FORMED WITH A CENTRAL OPENING THERETHROUGH HAVING AN UPPER PORTION DEFINED BY A CONICAL FACE AND A LOWER PORTION OF POLYGONAL CROSS SECTION AND DEFINED BY FACES INTERSECTING EACH OTHER ALONG EDGES SUBSTANTIALLY PARALLEL TO THE AXIS OF SAID CONICAL FACE AND INTERSECTING SAID CONICAL FACE OF SAID UPPER PORTION ALONG INTERSECTION LINES HAVING THEIR HIGHEST POINTS AT SAID EDGES AND CURVING DOWNWARDLY THEREFROM TOWARD SAID BOTTOM FACE; A BARREL ARBOR HAVING A SHOULDER ENGAGING SAID BOTTOM FACE OF SAID RATCHET WHEEL AND A RATCHET WHEEL RECEIVING END PORTION HAVING A CROSS SECTION SUBSTANTIALLY EQUAL TO SAID CROSS SECTION OF SAID LOWER PORTION OF SAID CENTRAL OPENING AND PROJECTING UPWARDLY FROM 